This invention relates to a signal processing apparatus, preferably used in a dubbing apparatus for recording a picture signal taken by, for example, an electronic camera or the like onto another recording medium.
FIG. 4 is a block diagram showing the configuration of a conventional dubbing apparatus, wherein reference numerals 34 and 36 designate a reproducing device and a recording device, respectively. A signal transmitted from the reproducing device 34 is recorded by the recording device 36.
A signal in which two color difference signals R-Y and B-Y are line-sequentially alternately aligned on every horizontal scanning line as shown in FIG. 5A and a luminance signal Y which has been FM-modulated are reproduced from, for example, a video floppy disk of an electronic still camera and are respectively supplied to terminals 10 and 28 of the reproducing device 34.
The color difference signal supplied to the terminal 10 is delayed by 1 H (H means a horizontal scanning period) by a 1 H delay (DL) circuit 14 (FIG. 5C), further delayed by 1 H by another 1 H delay (DL) circuit 16 (FIG. 5D), and then supplied to an adder 18. The color difference signal which has not been delayed by the 1 H delay circuits 14 and 16 is also supplied to the adder 18 so that this undelayed color difference signal is added to the signal supplied from the 1 H delay circuit 16 (FIG. 5E). The output of the adder 18 is supplied to a contact 20a of a switch circuit 20 as well as to a contact 22b of a switch circuit 22. An output of the 1 H delay circuit 14 is supplied to the other contacts 20b and 22a of the respective switch circuits 20 and 22.
On the other hand, a detection circuit (IDDET) 12 detects the color components on every line of the line-sequentially aligned color difference signals supplied from the terminal 10 and produces a line index signal LI serving as a control signal, FIG. 5B, which, for example, becomes logic "1" for a line on which a color difference signal B-Y is disposed, and logic "0" for a line on which a color difference signal R-Y is disposed. The line index signal is supplied to the switch circuits 20 and 22 as a switching signal. The switch circuits 20 and 22 are switched to the upper contacts 20a and 22a in the drawing when the line index signal is logic "1", and to the lower contacts 20b and 22b when the line index signal is logic "0".
In the output of the 1 H delay circuit 14, as shown in FIG. 5C, a color difference signal R-Y is disposed when the line index signal is logic "1", while a color difference signal B-Y is disposed when the line index signal is logic "0". Further, in the output of the adder 18, as shown in FIG. 5E, a color difference signal B-Y is disposed when the line index signal is logic "1", while a color difference signal R-Y is disposed when the line index signal is logic "0". Accordingly, as shown in FIGS. 5G and 5F, the color difference signals B-Y and R-Y are outputted from the switch circuits 20 and 22 respectively.
When the switch circuit 20 outputs a color difference signal B-Y of the n-th line, the switch circuit 22 outputs a sum signal of color difference signals R-Y of the (n-1)th and (n+1)th lines. Similarly, when the switch circuit 22 outputs a color difference signal R-Y of the n-th line, the switch circuit 20 outputs a sum signal of color difference signals B-Y of the (n-1)th and (n+1)th lines. That is, two color difference signals are made to be simultaneous.
The two simultaneous color difference signals are supplied from terminals 24 and 26 of the reproducing device 34 to contacts 44b and 44a of a switch circuit 44 through terminals 38 and 40 of the recording device 36, respectively.
On the other hand, the FM luminance signal supplied to the terminal 28 is demodulated by a demodulation circuit 30. The demodulated signal is supplied from a terminal 32 of the reproducing device 44 to a modulation circuit 46 through a terminal 42 of the recording device 36. The signal modulated by the modulation circuit 46 is supplied to a not-shown head so as to be recorded onto a not-shown recording medium.
The luminance signal supplied to the terminal 42 is also supplied to a horizontal synchronizing (Hsync) separation circuit 48, which separates a horizontal synchronizing signal HD from the luminance signal and supplies the separated signal HD to a switching-signal generation circuit 50. The latter controls the switching of the switch circuit 44 in synchronization with the supplied horizontal synchronizing signal, so that the contacts 44a and 44b are alternately switched for every line. Accordingly, as shown in FIG. 5I, an output of the switch circuit 44 is a line-sequential signal in which color difference signals R-Y and B-Y are alternately aligned on every line.
This signal is supplied to a not-shown frequency modulator so as to be frequency-modulated, and then supplied to a head so as to be recorded on a recording medium with the luminance signal.
In such an apparatus, however, the switching of the switch circuit 44 does not always correspond to the line index signal, so that there is a possibility that a color difference signal on one line is not selected as shown in FIG. 5I, but instead a sum signal obtained by adding two color difference signals separated from each other by two lines is selected, as shown in FIG. 5H. Thus, when such a sum signal obtained by adding the color difference signals on two lines is recorded, the quality of a picture is deteriorated correspondingly.
The assignee of this application has previously proposed an apparatus as shown in FIG. 6 and in Japanese Utility Model Unexamined Publication No. Hei-1-124784. In this apparatus, the reproducing device 34 and the recording device 36 are provided with terminals 52 and 54, respectively. A line index signal produced from the detection circuit 12 is supplied to the switch circuit 44 through the terminals 52 and 54 as a switching signal in place of the horizontal synchronizing signal. That is, in this apparatus, the switch circuit 44 is switched correspondingly to the line index signal, so that a signal obtained by adding color difference signals on two lines is prevented from being selected.
However, the apparatus shown in FIG. 6 has a disadvantage in that although a correct color difference signal is selected when a line index signal exists in the case where a video signal is recorded from a recording device such as a video camera, two color difference signals cannot be line-sequentially aligned when no line index signal exists.